Driver circuitry

ABSTRACT

A clutch or similar device electronic driver circuit whereby the clutch coil is connected in series with a variable resistance circuit, such as a parallel connected diode and resistor, which displays a first resistance when current flows through the serial combination in a first direction to actuate the clutch and a second greater resistance when current flows through the serial combination in an opposite direction to produce a small reverse bias voltage across the coil which serves to demagnetize it and thus increase the speed of response of the coil as it is deactuated. Two electronic switching circuits are connected to the load for reversing the polarity of the voltage across the load and accordingly actuate and demagnetize the clutch alternately in response to input signals. A high transient current is produced at the time the coil is activated to ensure a quick response from the clutch. In the embodiment set forth below, the load comprises two alternately connected coils each having a variable resistance connected in series with it so that one coil is actuated while the other is being demagnetized and vice versa.

[451 May 29, 1973 DRIVER CIRCUITRY Charles D. Pugh, Burlington, NC.

[73] Assignee: Burlington Industries, Inc., Greensboro,N.C.

[22] Filed: July I, 1971 [21] Appl. No.: 158,965

[75] Inventor:

[57] ABSTRACT A clutch or similar device electronic driver circuit whereby the clutch coil is connected in series with a variable resistance circuit, such as a parallel con-- nected diode and resistor, which displays a first resistance when current flows through the serial combination in a first direction to actuate the clutch and a second greater resistance when current flows through the serial combination in an opposite direction to 317/137 3l7/DIG' i 1 ,5 produce a small reverse bias voltage across the coil which serves to demagnetize it and thus increase the [58] Field of Search ..3l7/DIG. 4, 7,137,

340/176 speed of response of the c011 as it is deactuated. Two electronic switching circuits are connected to the load [56] References Cited for reversing the polarity of the voltage across the load and accordingly actuate and demagnetize the clutch UNITED STATES PATENTS alternately in response to input signals. A high 2,424,243 7 1947 Lowell ..340/l76 transient cumin is Pmduced at the time the is 2,992 3 7 19 1 v ltf t J 340/147 PC tivated to ensure a quick response from the clutch. In 3,070,732 12/1962 Crandall et a1". ..340/l76 th em dim t s t rth below, t ad mpr s s ,0 96 Pickens -...3l7/DlG. 4 two alternately connected coils each having a variable 1 Kennedy 4 resistance connected in series so that one coil is actuated while the other is being demagnetized and Primary Examiner-L. T. H1x vice versa Attorney-Cushman, Darby & Cushman 10 Claims, 3 Drawing Figures A. O 1 7 D as "-26 A 30 B -.-L 0/4 2255,5562

BZ e 2 156 ia WC fzicrfia/v/c sw/rc/v .SW/TC/r 0c. rozmae 34 L J SOURCE 250 r/eoxv/c DRIVER CIRCUITRY The invention relates to a driver circuit for a clutch or similar device.

Electric clutches, brakes, solenoids and similar devices operate by storing energy which flows in the form of an electric current through a coil and using that energy to perform a mechanical function. As a result of that storage, the coil becomes magnetized while the clutch remains actuated and normally retains and builds up a residual magnetism after current ceases flowing through it and the clutch is deactuated. This residual magnetism can build up to a level where it considerably reduces the time it takes for the clutch, brake, solenoid, etc. to become deactuated after current ceases flowing through it.

A further problem with such devices is that the instantaneous current required to energize or collapse the magnetic field is much greater than the normal operating current required. These transient currents tend to burn, pit and in general deteriorate conventional electrical contacts, when such contacts are used to interrupt and complete the current path through the load. Such deterioration is magnified where the switching speed is rapid and, indeed, the physical speed with which the contacts can be opened and closed severely limits the speed with which theclutch, coil or brake can be alternately actuated and deactuated.

The present invention relates to a novel driver circuitry whereby a small reverse bias voltage is provided across the coil while it is deactuated so thatthe coil is demagnetized. This is accomplished in the embodiment of the invention set forth below by providing a variable resistance circuit in series with the coil so that the serial combination comprises a load. The resistance circuit, which is preferably a resistor connected in parallel with a diode, displays a first resistance when current flows through the combination in a first direction so that the diode shunts the resistor and the coil is actuated and a second resistance when current flows through the combination in an opposite direction such that the diode is turned off and a small reverse bias voltage sufficient for demagnetization is provided across the coil.

According to the embodiment of the invention set forth below, this current reversal is preferably accom' plished by electronic circuitry which can actuate and deactuate the coil much quicker than any mechanical contacts, and can safely switch comparatively large amounts of power with relatively small expenditures of power. Two electronic switches are connected to each other, to an input driver circuit, to a DC. power supply and each to one side of the load. When the input driver circuit receives a first signal, one of the electronic switches applies a low voltage to the side of the load to which it is connected while the other electronic switch applies a high voltage to the sideof the load to which it is connected. When, thereafter, the input driver circuit receives a second signal the polarity of the voltage across the load is reversed. Whenever current flows through a coil to actuate it, a transient voltage is produced across the coil which causes it to be quickly actuated and, in the case of a clutch, to securely and quickly grab.

Many of the objects and purposes of the invention will become clear from the following detailed description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a block diagram of one embodiment of this invention.

FIG. 2 shows a detailed schematic of the embodiment of FIG. 1.

FIG. 3 shows a plot of the voltages across the coils in the schematic of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIG. 1 which shows a block diagram of one embodiment of the novel driver circuitry of this invention. As mentioned above, this circuit includes an electronic switch driver 20, which is adapted for receiving at least first and second input signals, either on separate lines or on the same line. When the first input signal is received, the driver circuitry produces a suitable signal which is received by electronic switch 22, connected to driver 20 as shown, so that switch 22 applies at least a substantial portion of the voltage of a conventional DC voltage source 24, developing,.for example, volts D.C., to terminal A of load 26, which is preferably comprised of at least one coil 30 of an electric clutch, a solenoid or other similar device through which current flows to generate a magnetic field andstore energy which is then used to accomplish a mechanical function. Coil 30 is connected in series with a variable resistor 32, which exhibits one resistance when current flows through it in a first direction and a different resistance when the current flows through it in the opposite direction.

Electronic switch 22 is connected to a second electronic switch 34, as is switch driver 20, so that when switch 22 applies a substantial portion of the voltage provided by source 24 to terminal A in response to the first input signal received by switch driver 20, electronic switch 34 applies a voltage to terminal B which is lower than the voltage applied to terminal A so that current flows through the load 26 in the direction indicated by arrow 38. Electronic switch 34 as well as electronic switch 22 is connected to ground via resistor 40 so that the voltage which switch 34 connects to terminal B, when switch driver 20 receives the first input signal, may be produced by directly connecting resistor 40 to terminal B.

Because of the substantial inductance which normally is inherent in coil 30, the transient current through load 26 in the direction of arrow 38 at the time that switching occurs is substantial and produces a sharp voltage pulse across coil 30 which quickly generates the magnetic field and stores sufficient energy so that the mechanical function is accomplished quickly. In embodiments where the coil 30 is associated with a clutch this transient pulse operates to quickly grab the clutch. Operation in this fashion has been found to greatly improve the lifetime and reliability of the clutch in contrast to most arrangements in which it is not applied so abruptly.

The current flow through coil 30 in the direction shown by arrow 38 continues with the voltage across coil 30 during the steady state period being sufficient to perform the mechanical function desired. Thereafter, when the second input signal is applied to electronic switch driver 20, a signal is produced and applied by driver 20 to electronic switch 34 which causes switch 34 to apply a voltage to terminal B which is a substantial portion of the voltage provided by source 24, and at the same time causes switch 22 to apply a voltage to terminal A which is substantially less than the voltage applied to terminal B, so that the polarity across load 26 is reversed and current begins to flow through load 26 in a direction opposite that shown by arrow 38..

However, as mentioned above, variable resistor 32 is designed to display a high resistance when current is flowing in a direction opposite to that represented by arrow 38, and to display a low resistance when current is flowing in the direction of arrow 38. However, sufficient reverse current does flow through load 26 and coil 30 to apply a small reverse bias voltage across coil 30 which operates to demagnetize the coil. As mentioned above, this demagnetization occurs each time that the current is reversed so that the delay in causing deactuating a magnetized coil after current ceases flowing through it is eliminated.

Reference is now made to FIG. 2 which shows a detailed schematic of one circuit for carrying out the functions of the circuitry shown in block diagram shown in FIG. 1 and to FIG. 3 which shows the voltage across the two coils operated by the circuitry of FIG. 2. In this arrangement, driver circuitry 20 includes a transistor 50 which has its base connected via resistor 52 to slub in terminal 54. The base of transistor 50 is also connected to ground via resistor 56. Thus, when the slub in terminal 54 is essentially at ground so that transistor 50 is turned on and driven into the saturated region by the voltage existing between the base and the emitter thereof, as applied by resistor 60, saturated transistor 50 applies a low voltage, essentially at ground, to the base of transistor 62 via resistor 64 so that transistor 62 is kept in a nonconductive condition. Because transistor 62 is non-conductive, a high voltage is applied to the bases of transistors 64 and 66 so that these transistors are driven deep into their saturation regions, and accordingly ground is effectively applied to the collector of transistor 64 via resistor 40 and to the collector of transistor 66. Since the collector of transistor 66 is essentially at ground, transistor 68 is maintained in its non-conductive state. Further, the collector of transistor 64 is connected to the base of transistor 70 via resistor 69 and line 71, so that transistor 64 applies an input of essentially ground to the base of transistor 70 which keeps transistor 70 in its nonconductive condition. The base of transistor 72 is connected to the collector of transistor 70 which is connected to power supply line 75 by resistance 74, so that when transistor 70 is non-conductive and transistor 68 is non-conductive, transistor 72 is conductive and applies a high voltage to terminal B ofload 26. Power line 75 connects, as shown, to conventional D.C. power supply 24 which inclues full wave rectifying diodes 77, fuse 79 and smoothing capacitor 81.

The base of transistor 74 is similarly connected to terminal B via resistor 76 such that when terminal B is at the high voltage and transistor 64 is in its conductive condition, a voltage is applied between the base and emitter of transistor 74 which drives that transistor into its saturation region, thus essentially grounding the base of transistor 80 via resistor 40 so that transistor 80 remains in its non-conductive condition. In this fashion, a voltage of a first polarity is established between terminals A and B so that current flows through the load in a direction opposite to that indicated by arrow 38. A capacitance 82 is connected to the collectors of transistors 72 and for preventing the voltage at that point from collapsing too rapidly when the electronic switches which include these transistors shift from their first to second output conditions to reverse the polarity of the voltage across load 26 and the direction of current flow through that load.

When terminal B is at a higher voltage than terminal A as described above, current flows in a direction opposite to that indicated by arrow 38 through load 26 and, more particularly, through a first circuit comprised of parallel connected resistor 86 and diode 88, which are connected in series with a slub clutch coil 90, and through a second circuit comprised of a further parallel connected resistor 94 and diode 96, which are connected in series as shown with a space clutch coil 100. Resistor 86 and diode 88 in effect form a variable resistance element which has a relatively low resistance as current flows through load 26 in the direction of arrow 38 and diode 88 shunts resistor 86. Conversely when current flows through resistor 86, diode 88 and slub clutch coil 90 in a direction opposite to that indicated by arrow 38, no current flows through diode 88, which is biased in its non-conductive condition and the resistance presented by the parallel connected resistor 86 and diode 88 is substantial. Thus, when current flows through load 26 in the direction indicated by an arrow 38, the voltage drop across slub clutch coil 90, as shown in FIG. 3, is essentially the voltage drop across the terminals A and B of load 26, and when current flows in the opposite direction, the voltage drop across the slub clutch coil 90 is a small portion thereof and is of an opposite polarity.

The circuit is connected such that when current flows in the direction of arrow 38 and the voltage across slub clutch coil 90 is essentially the voltage between terminals A and B of load 26, the energy which the coil stores is sufficient to perform the mechanical function of the coil. When current flows in the opposite direction, the voltage across slub clutch coil 90 is just sufficient to de-magnetize that coil, as discussed above. A resistor 104 and neon light 106 are connected in parallel with the slub clutch coil 90 in order to indicate when slub clutch coil 90 is in operation.

Similarly, a second coil 100, termed the space clutch coil, is connected in series with resistance 94 and diode 96 as shown, such that when the voltage at terminal B exceeds the voltage at terminal A, the parallel connected resistor 94 and diode 96 present a relatively low resistance because diode 96 essentially shunts resistor 94 so that the voltage across space clutch coil 100 is essentially the voltage between terminals A and B, and the clutch associated with coil 100 is actuated to perform its mechanical function. Similarly, when current flows through load 26 in the direction of arrow 38 and the voltage at terminal A is greater than the voltage at terminal B, the resistance presented by the parallel connected resistor 94 and diode 96 is substantial, such that a small residual voltage across coil 100 results which is of an opposite polarity and which is sufficient to de-magnetize the coil. In the particular configuration shown in FIG. 2, the two coils 80 and 100 are actuated and de-magnetized alternately with one coil being demagnetized while the other coil is actuated. This particular arrangement has been found to be particularly advantageous for actuating the clutches termed the space and slub clutches which are employed in producing slub yarn. Further, details of one such device are set forth in a Pugh application filed herewith entitled Control Mechanism for Producing Random-Like Effects on Textile Materials and the disclosure of that application is explicitly incorporated herein by reference. A variable resistor 110 is connected in series with load 26 for varying the current flow through the load to any desired level.

When a second signal is supplied to slub in terminal 54 which is high with respect to ground, transistor 50 is driven into its non-conductive region, thus causing a high voltage to be applied to the base of transistor 62 which becomes conductive, applying ground to the base of transistor 66 and to the base of transistor 64. Both of these transistors are thus driven into their nonconductive states. The shifting of transistor 66 from its conductive to its non-conductive condition applies a high input to the base of transistor 68 whose emitter is connected to ground by resistor 40 so that transistor 68 shifts to its conductive condition applying a low voltage essentially at ground to terminal B. The voltage at terminal B is applied to the base of transistor 74 via resistor 76 so that transistor 74 is similarly driven into its non-conductive region, permitting transistor 80 to become conductive and applying a high voltage to terminal A.

Similarly, a high voltage is now applied to the base of transistor 70 via line 71 and resistor 69 such that tran sistor 70 is driven into its conductive region, in turn causing transistor 72 to become non-conductive. The current now flows through load 26 from terminal A to terminal B via transistor 80, transistor 68 and resistor 40. Thus the current applied across the terminals A and B is the same in each instance; only the polarity of the voltage across load 26 has been changed.

Control in terminals 120 and 122 can be employed to hold the circuit in either of its output conditions irregardless of the input applied to terminal 54. If a high input is applied to terminal 122, that input remains as the input to the base of transistor 62 regardless of whether or not transistor 50 thereafter is driven into its conductive region in response to a low input on slub in terminal 54. Similarly, when a high input is applied to control in terminal 120, transistor 122 is driven into its conductive condition and applies a voltage of essentially ground to the input of transistor 62 so that transistor remains in a non-conductive condition.

As mentioned above, while this particular circuit has been found to be especially advantageous in controlling the operation of clutches which are employed in making slub yarn, such circuitry can be employed in a wide variety of application for controlling any of a number of different devices such as clutches, brakes, etc. in which current through a coil or the like is employed to store energy in a magnetic field and use that energy to perform a mechanical function. For example, the circuit has also been found to be particularly successful in operating the feed circuit on a drapery cutting table where the circuit is actuated by a push button to operate an electric clutch with the clutch delivering a specified length of cloth to the cutting table. Once the specified length was reached, the circuit is switched by a photocell unit to relieve the clutch and act as a brake. The fast switching characteristics of the circuit shown in FIG. 2 has been found to substantially improve the accuracy of control as compared to conventional relay type switches previously used on cutting table controls.

This circuit has been found to provide very fast switching as compared to well known microswitch and relay switching characteristics, both because of the relatively high transient voltage which is applied across the coil to actuate it, and the small reversible polarity voltage which is applied across the coil, when the circuit is not in operation, to de-magnetize it. It has been found that this circuit provides an impulse voltage up to percent of the operating voltage in switching brakes, clutches and solenoid, and this permits increased speed in magnetic field build-up and increases speed in operation of the device. This circuit, of course, has no moving parts and has been found to be capable of dissipating switching power troubles caused by stored energy without any harm to the circuit.

In the specific circuit of FIG. 2, representative values are given for each of the elements but no limitation to these values is intended.

What is claimed is:

l. A driver circuit for operating devices of the type in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising:

circuit means, connected in series with said portion,

having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant, but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion, and

means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized.

2. A driver circuit as in claim 1 wherein said circuit means is a resistor and a diode connected in parallel with said resistor so that said diode conducts current when said given voltage of said first polarity is applied to said serially connected circuit means and portion and does not conduct current when said given voltage of said opposite polarity is applied to said serially connected circuit means and portion.

3. A driver circuit as in claim 1 wherein said device is a clutch and said portion is a coil and including said coil.

4. A circuit as in claim 1 further including second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized.

5. A circuit as in claim 1 wherein said providing means includes means for providing a DC voltage, first electronic switch means having a first condition connecting at least a portion of said DC voltage to one side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said one side, second electronic switch means having a first condition connecting at least a portion of said DC voltage to the other side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said other side, and third electronic switch means connected to said first and second electronic switch means for receiving said first and second input signals, causing said first switch means to shift from its first to its second condition and said second switch means to shift from its second to its first condition when said first input signal is received and causing said first switch means to shift from its second to its first condition and said second switch means to shift from its first to its second condition when said second input signal is received.

6. A circuit as in claim 5 further including a variable resister serially connected to said serially connected portion and circuit means. a

7. A circuit as in claim 5 wherein said electronic switch means each includes at least a single transistor.

8. A driver circuit for operating first and second clutches in which electrical current flows through a coil thereof so that electrical energy is stored for accomplishing a mechanical clutch function when the stored energy exceeds a given level comprising:

first circuit means, connected in series with said coil of said first clutch, having a first resistance value when a given voltage across said serially connected circuit means and first clutch coil is a first polarity so that current flows through said serially connected circuit means and first clutch coil in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and first clutch coil is the opposite polarity so that significant but less current flows through said serially connected circuit means and first clutch coil in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said first clutch coil,

means connected to said circuit means and first clutch coil for providing said given voltage of said first polarity across said serially connected first clutch and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said first clutch coil and magnetization of said first clutch coil and for providing said given voltage of said opposite polarity across said serially connected circuit means and first clutch coil when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said first clutch coil causing smaller but significant current flow through said first clutch coil so that said first clutch coil is demagnetized, and

second circuit means connected in series with said second clutch coil, said serially connected second circuit means and second clutch coil being connected in parallel with said serially connected first circuit means and first clutch coil and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and second clutch coil is said second polarity so that current flows through said serially connected second circuit means and second clutch coil in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and second clutch coil is said first polarity so that current flows through said serially connected second circuit means and second clutch .coil in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said provid ing means provides said given voltage of said first polarity across said serially connected second clutch coil and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said second clutch coil so that said second clutch coil is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and second clutch coil when said second input signal is received so as to produce a larger voltage of the opposite polarity across said first clutch coil so that said first clutch coil is magnetized.

9. A driver circuit for operating devices of the type in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising:

first circuit means, connected in series with said portion, having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion said circuit means including a resistor and a diode connected in parallel with said resistor so that said diode conducts current when said given voltage of said first polarity is applied to said serially connected circuit means and portion and does not conduct current when said given voltage of said opposite polarity is applied to said serially connected circuit means and portion,

means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized and second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance valve when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said provid- 1 ing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized said second circuit means including a second resistor and a second diode connected in parallel with said second resistor so that said second diode conducts current when said given voltage of said first polarity is applied to said in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising:

first circuit means, connected in series with said portion, having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant, but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion,

means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized,

second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized,

said providing means including means for providing a DC voltage, first electronic switch means having a first condition connecting at least a portion of said DC voltage to one side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said one side, second electronic switch means having a first condition connecting at least a portion of said DC voltage to the other side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said other side, and third electronic switch means connected to said first and second electronic switch means for receiving said first and second input signals, causing said first switch means to shift from its first to its second condition and said second switch means to shift from its second to its first condition when said first input signal is received and causing said first switch means to shift from its second to its first condition and said second switch means to shift from its first to its second condition when said second input signal is received. 

1. A driver circuit for operating devices of the type in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising: circuit means, connected in series with said portion, having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant, but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion, and means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized.
 2. A driver circuit as in claim 1 wherein said circuit means is a resistor and a diode connected in parallel with said resistor so that said diode conducts current when said given voltage of said first polarity is applied to said serially connected circuit means and portion and does not conduct current when said given voltage of said opposite polarity is applied to said serially connected circuit means and portion.
 3. A driver circuit as in claim 1 wherein said device is a clutch and said portion is a coil and including said coil.
 4. A circuit as in claim 1 further including second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage Of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized.
 5. A circuit as in claim 1 wherein said providing means includes means for providing a DC voltage, first electronic switch means having a first condition connecting at least a portion of said DC voltage to one side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said one side, second electronic switch means having a first condition connecting at least a portion of said DC voltage to the other side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said other side, and third electronic switch means connected to said first and second electronic switch means for receiving said first and second input signals, causing said first switch means to shift from its first to its second condition and said second switch means to shift from its second to its first condition when said first input signal is received and causing said first switch means to shift from its second to its first condition and said second switch means to shift from its first to its second condition when said second input signal is received.
 6. A circuit as in claim 5 further including a variable resister serially connected to said serially connected portion and circuit means.
 7. A circuit as in claim 5 wherein said electronic switch means each includes at least a single transistor.
 8. A driver circuit for operating first and second clutches in which electrical current flows through a coil thereof so that electrical energy is stored for accomplishing a mechanical clutch function when the stored energy exceeds a given level comprising: first circuit means, connected in series with said coil of said first clutch, having a first resistance value when a given voltage across said serially connected circuit means and first clutch coil is a first polarity so that current flows through said serially connected circuit means and first clutch coil in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and first clutch coil is the opposite polarity so that significant but less current flows through said serially connected circuit means and first clutch coil in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said first clutch coil, means connected to said circuit means and first clutch coil for providing said given voltage of said first polarity across said serially connected first clutch and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said first clutch coil and magnetization of said first clutch coil and for providing said given voltage of said opposite polarity across said serially connected circuit means and first clutch coil when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said first clutch coil causing smaller but significant current flow through said first clutch coil so that said first clutch coil is demagnetized, and second circuit means connected in series with said second clutch coil, said serially connected second circuit means and second clutch coil being connected in parallel with said serially connected first circuit means and first clutch coil and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and second clutch coil is said second polarity so that current flows Through said serially connected second circuit means and second clutch coil in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and second clutch coil is said first polarity so that current flows through said serially connected second circuit means and second clutch coil in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected second clutch coil and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said second clutch coil so that said second clutch coil is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and second clutch coil when said second input signal is received so as to produce a larger voltage of the opposite polarity across said first clutch coil so that said first clutch coil is magnetized.
 9. A driver circuit for operating devices of the type in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising: first circuit means, connected in series with said portion, having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion said circuit means including a resistor and a diode connected in parallel with said resistor so that said diode conducts current when said given voltage of said first polarity is applied to said serially connected circuit means and portion and does not conduct current when said given voltage of said opposite polarity is applied to said serially connected circuit means and portion, means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized and second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing iN said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance valve when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized said second circuit means including a second resistor and a second diode connected in parallel with said second resistor so that said second diode conducts current when said given voltage of said first polarity is applied to said serially connected second circuit means and another portion and does not conduct current when said given voltage of said opposite polarity is applied to said serially connected second circuit means and another portion.
 10. A driver circuit for operating devices of the type in which electrical current flows through a portion thereof so that electrical energy is stored for accomplishing a mechanical function when the stored energy exceeds a given level comprising: first circuit means, connected in series with said portion, having a first resistance value when a given voltage across said serially connected circuit means and portion is a first polarity so that current flows through said serially connected circuit means and portion in a first direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when a given voltage across said serially connected circuit means and portion is the opposite polarity so that significant, but less current flows through said serially connected circuit means and portion in an opposite direction and so that said current flowing in said opposite direction will not cause sufficient energy to be stored to accomplish a function but will establish a significant voltage across said portion, means connected to said circuit means and portion for providing said given voltage of said first polarity across said serially connected portion and circuit means, when a first input signal is received, so as to produce a voltage of said first polarity across said portion and magnetization of said portion and for providing said given voltage of said opposite polarity across said serially connected circuit means and portion when a second input signal is received so as to produce a smaller voltage of the opposite polarity across said portion causing smaller but significant current flow through said portion so that said portion is demagnetized, second circuit means connected in series with another portion of another device, said serially connected second circuit means and another portion being connected in parallel with said serially connected first circuit means and portion and said second circuit means having a first resistance value when said given voltage across said serially connected second circuit means and another portion is said second polarity so that current flows through said serially connected second circuit means and another portion in said opposite direction and so that said current flowing in said first direction is sufficient to store sufficient energy to accomplish said function and having a second and greater resistance value when said given voltage across said serially connected second circuit means and another portion is said first polarity so that current flows through said serially connected second circuit means and another portion in said first direction and so that said current flowing in said first direction will not cause sufficient energy to be stored to accomplish said function, and wherein said providing means provides said given voltage of said first polarity across said serially connected another portion and second circuit means, when said first input signal is received so as to produce a voltage of said first polarity across said another portion so that said another portion is demagnetized and provides said given voltage of said opposite polarity across said serially connected second circuit means and another portion when said second input signal is received so as to produce a larger voltage of the opposite polarity across said portion so that said portion is magnetized, said providing means including means for providing a DC voltage, first electronic switch means having a first condition connecting at least a portion of said DC voltage to one side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said one side, second electronic switch means having a first condition connecting at least a portion of said DC voltage to the other side of said serially connected circuit means and portion and a second condition connecting a lower voltage to said other side, and third electronic switch means connected to said first and second electronic switch means for receiving said first and second input signals, causing said first switch means to shift from its first to its second condition and said second switch means to shift from its second to its first condition when said first input signal is received and causing said first switch means to shift from its second to its first condition and said second switch means to shift from its first to its second condition when said second input signal is received. 